Project

# Title Team Members TA Documents Sponsor
17 Shower Music Controller
 Amar Patel
Shalin Joshi
Varnith Aleti
# Shower Music Controller

Team Members:
- Shalin Joshi (shalinj2)
- Amar Patel (amarcp2)
- Varnith Aleti (valet3)

# Problem

People often like to listen to music when they are in the shower, but it is very inconvenient to control/play specific music with wet hands, foggy screens, and with devices that aren't waterproof. If the person wants to switch the song, it leads to issues of getting the phone wet, having to step out of the shower, or just being stuck with whatever song is being played.

# Solution

The solution is a waterproof device that can be stuck to a shower wall, which allows the user to play, pause, skip, and even search for their playlists/songs from Spotify. This device will act as a Bluetooth remote interface to connect to a phone companion app. The app will be able to call the Spotify API and communicate with the device in order to do each task. The device will include buttons for playback actions and D-Pad buttons to navigate the UI on a screen.

# Solution Components

## Subsystem 1 - Embedded UI (Screen + Buttons)

Displays different menus and music lists (search, my playlists, now playing) and captures user input by using physical buttons. The buttons will be different ones for playback controls (play, pause, skip, volume) and a d-pad to navigate through the menus and songs on the UI. D-pad implemented using 4 tactile switches (UP/DOWN/LEFT/RIGHT) arranged in a cross layout plus a center SELECT switch, all mounted on the PCB and covered through a waterproof silicone membrane.

Components:
- SPI TFT display module using ILI9341 controller
- Tactile Switches

## Subsystem 2 - Microcontroller + BLE Communication

Runs the software for the button controls and has Bluetooth communication with the phone. Sends commands (play/pause, search query, select track) and receives results/status updates from the phone.

Components:
- ESP32 Microcontroller

## Subsystem 3 - Phone Companion App + Spotify Integration

Handles Spotify authentication and all Web API requests. Translates Bluetooth messages from the device into Spotify actions and returns data back to the device. The app will do all the music control and Spotify connections and communicate with the device in order to know which actions to perform

Components:
- Mobile app using Swift or React
- Spotify WebAPI

## Subsystem 4 - Power, Charging, and Water-resistant Enclosure

Provides safe portable power, charging, voltage regulation, and physical waterproofing suitable for shower spray/steam. This subsystem will ensure that the device and its components are water-resistant and have charging capabilities. We will make sure that water doesn’t harm our device by enclosing it in a 3D-printed enclosure. The screen will be covered by a clear acrylic/polycarbonate display window, and the buttons will be lined with a silicone membrane. When the user wants to charge the device, they will remove it from the enclosure and shower and charge it elsewhere.

Components:
- LiPo Battery
- Li-ion charger IC/module (USB powered charging)
- 3.3V regulator for MCU and display
- Waterproof enclosure elements
- 3D printed enclosure for the device board and circuitry
- Clear acrylic/polycarbonate display window
- Silicone membrane for buttons

# Criterion For Success
- From the shower device, the user can successfully perform different playback actions with a maximum 1-2 seconds of delay: Play/Pause, Next Track, Previous Track, Volume Up/Down
- Users can enter a search query using buttons, submit it, receive at least 5 search results on the device screen, select one, and start playback.
- Device can connect through bluetooth to phone companion app and remain connected through the entire duration of a shower
- Device remains functional after 5 minutes of exposure to shower spray/steam.
- Device operates for at least 2 hours of active use on a full charge.

Instant Nitro Cold Brew Machine

Danis Heto, Mihir Vardhan

Instant Nitro Cold Brew Machine

Featured Project

# Instant Nitro Cold Brew Machine

Team Members:

- Mihir Vardhan (mihirv2)

- Danis Heto (dheto3)

# Problem

Cold brew is made by steeping coffee grounds in cold water for 12-18 hours. This low-temperature steeping extracts fewer bitter compounds than traditional hot brewing, leading to a more balanced and sweeter flavor. While cold brew can be prepared in big batches ahead of time and stored for consumption throughout the week, this would make it impossible for someone to choose the specific coffee beans they desire for that very morning. The proposed machine will be able to brew coffee in cold water in minutes by leveraging air pressure. The machine will also bring the fine-tuning and control of brewing parameters currently seen in hot brewing to cold brewing.

# Solution

The brew will take place in an airtight aluminum chamber with a removable lid. The user can drop a tea-bag like pouch of coffee grounds into the chamber along with cold water. By pulling a vacuum in this chamber, the boiling point of water will reach room temperature and allow the coffee extraction to happen at the same rate as hot brewing, but at room temperature. Next, instead of bringing the chamber pressure back to atmospheric with ambient air, nitrogen can be introduced from an attached tank, allowing the gas to dissolve in the coffee rapidly. The introduction of nitrogen will prevent the coffee from oxidizing, and allow it to remain fresh indefinitely. When the user is ready to dispense, the nitrogen pressure will be raised to 30 PSI and the instant nitro cold brew can now be poured from a spout at the bottom of the chamber.

The coffee bag prevents the coffee grounds from making it into the drink and allows the user to remove and replace it with a bag full of different grounds for the next round of brewing, just like a Keurig for hot coffee.

To keep this project feasible and achievable in one semester, the nitrogenation process is a reach goal that we will only implement if time allows. Since the vacuum and nitrogenation phases are independent, they can both take place through the same port in the brewing chamber. The only hardware change would be an extra solenoid control MOSFET on the PCB.

We have spoken to Gregg in the machine shop and he believes this vacuum chamber design is feasible.

# Solution Components

## Brewing Chamber

A roughly 160mm tall and 170mm wide aluminum chamber with 7mm thick walls. This chamber will contain the brew water and coffee grounds and will reach the user-set vacuum level and nitrogenation pressure if time allows. There will be a manually operated ball valve spout at the bottom of this chamber to dispense the cold brew once it is ready. The fittings for the vacuum hose and pressure sensor will be attached to the screw top lid of this chamber, allowing the chamber to be removed to add the water and coffee grounds. This also allows the chamber to be cleaned thoroughly.

## Temperature and Pressure Sensors

A pressure sensor will be threaded into the lid of the brewing chamber. Monitoring the readings from this pressure sensor will allow us to turn off the vacuum pump once the chamber reaches the user-set vacuum level. A temperature thermocouple will be attached to the side of the brewing chamber. The temperature measured will be displayed on the LCD display. This thermocouple will be attached using removable JST connectors so that the chamber can be removed entirely from the machine for cleaning.

## Vacuum Pump and Solenoid Valve

An oilless vacuum pump will be used to pull the vacuum in the brewing chamber. A solenoid valve will close off the connection to this vacuum pump once the user-set vacuum pressure is reached and the pump is turned off. To stay within the $100 budget for this project, we have been given a 2-Stage 50L/m Oil Free Lab Vacuum Pump on loan for this semester. The pump will connect to the chamber through standard PTFE tubing and push-fit connectors

If time allows and we are able to borrow a nitrogen tank, an additional solenoid and a PTFE Y-connector would allow the nitrogen tank to connect to the vacuum chamber through the same port as the vacuum pump.

## LCD Display and Rotary Encoder

The LCD display allows the user to interact with the temperature and pressure components of the brewing chamber. This display will be controlled using a rotary encoder with a push button. The menu style interface will allow you to control the vacuum level and brew time in the chamber, along with the nitrogenation pressure if time allows. The display will also monitor the temperature of the chamber and display it along with the time remaining and the current vacuum level.

# Criterion For Success

- A successful cold brew machine would be able to make cold brew coffee at or below room temperature in ten minutes at most.

- The machine must also allow the user to manually control the brew time and vacuum level as well as display the brew temperature.

- The machine must detect and report faults. If it is unable to reach the desired vacuum pressure or is inexplicably losing pressure, the machine must enter a safe ‘stop state’ and display a human readable error code.

- The reach goal for this project, not a criterion for success, would be the successful nitrogenation of the cold brew.

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